A thermal model of an underwater welding system is first proposed in reference to existing knowledge. Energy balance in the molten pool area is discussed using the energy conservation laws. Electric heating in the base material due to the current field is mathematically analyzed. Boundary heat losses during underwater welding is experimentally correlated into a linear relationship on a log-log scale. This explains a new model which is responsible for the rapid cooling during underwater welding. Mathematical analyses on the welding heat flow problems are treated to explain the possible effects of thermal properties, boundary heat losses, and plate thickness. An improved method with the consideration of the difference in thermal conductivity of steel in solid and liquid states predicts better arc efficiency. A modified analytical solution based on the weld bead width, instead of the unknown input heat, can predict better temperature profiles due to welding. More elaborate numerical analysis is also discussed. Effects of arc power, welding speed, water temperature, plate thickness, and surface insulations on cooling rate in the heat-affected-zone in underwater welding are finally analyzed. The calculated cooling rates are used to predict the metallurgical structure in the heat-affected-zone. Some design criteria for underwater "wet" welding are summarized in the end of this thesis.

  • Corporate Authors:

    Massachusetts Institute of Technology

    Department of Ocean Engineering, 77 Massachusetts Avenue
    Cambridge, MA  United States  02139
  • Authors:
    • Tsai, C L
  • Publication Date: 1977-9

Subject/Index Terms

Filing Info

  • Accession Number: 00170519
  • Record Type: Publication
  • Source Agency: Massachusetts Institute of Technology
  • Report/Paper Numbers: PhD Thesis
  • Files: TRIS
  • Created Date: Mar 7 1978 12:00AM